Method of producing oxygen concentration cells

Abstract

An oxygen concentration cell having a high peeling resistance of the electrode and an excellent response property can be obtained by a method wherein electrode-adhering particles, which consist essentially of a specifically limited amount of stabilized or partially stabilized zirconia granulated particles having a spherical shape and a particle size of not smaller than 44 μm and a specifically limited amount of stabilized or partially stabilized zirconia fine particles having a particle size of not larger than 10 μm as a sintering aid, are applied and adhered to the surface of a matrix consisting of stabilized or partially stabilized zirconia, the resulting assembly is sintered to form monolithically a large number of convex portions on the matrix surface, an electrode is adhered to the matrix surface having the convex portions monolithically formed thereon, and further a heat-resistant ceramic protecting film is adhered to the electrode film.

What is claimed is: 
     
       1. A method for producing an oxygen concentration cell suitable for exposure to high temperature combustion gases which comprises the steps of: (a) forming a green matrix by press molding a stabilized or partially stabilized zirconia raw material powder;   (b) producing electrode-adhering particles made of stabilized or partially stabilized zirconia granulated particles which have a substantially spherical shape and which contain no less than fifty percent by weight of granulated particles having a size of at least 44 microns and no less than ten percent by weight of fine particles having a size of no greater than ten microns to act as a sintering aid, said electrode-adhering particles being produced through granulation by spray drying fine primary particles;   (c) preparing fluidized electrode-adhering particles by adding an organic binder to said electrode-adhering particles;   (d) applying said fluidized electrode-adhering particles to a surface of said green matrix;   (e) sintering the green matrix and the applied electrode-adhering particles to form a monolithic matrix having a plurality of convex portions on the surface of the sintered matrix;   (f) applying an electrode to the surface of the sintered matrix; and   (g) applying a heat-resistant ceramic protective film to the electrode.   
     
     
       2. The method of claim 1 in which said granulated particles have an average particle size of 50 to 100 μm. 
     
     
       3. The method of claim 1 in which the raw material powder of the press-molded matrix, the primary particles of the granulated particles and the fine particles of the sintering aid are all fine particles having a particle size of not larger than 10 μm and in which the electrode-adhering particles produced therefrom contain not less than 60% by weight of the granulated particles having a size not smaller than 44 μm. 
     
     
       4. The method of claim 1 in which the granulated particles are applied and adhered to the press-molded matrix surface in the form of one or several layers. 
     
     
       5. The method of claim 1 in which the granulated particles are first adhered to the press-molded matrix surface and then the fine particles are adhered to a film of the granulated particles to form a film of the electrode-adhering particles on the matrix surface. 
     
     
       6. The method of claim 1 in which the granulated particles are produced by granulating a raw material mixture of stabilized or partially stabilized zirconia raw material powders having up to 5% by weight of a sintering aid based on the amount of the zirconia raw material powders.